[PATCH 1/4] rust: macros: fix usage of `#[allow]` in `quote!`

[Benno Lossin <benno.lossin@proton.me>]

When using `quote!` as part of an expression that was not the last one
in a function, the `#[allow(clippy::vec_init_then_push)]` attribute
would be present on an expression, which is not allowed.
This patch refactors that part of the macro to use a statement instead.

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
---
 rust/macros/quote.rs | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs
index c8e08b3c1e4c..dddbb4e6f4cb 100644
--- a/rust/macros/quote.rs
+++ b/rust/macros/quote.rs
@@ -39,12 +39,14 @@ impl ToTokens for TokenStream {
 /// [`quote_spanned!`](https://docs.rs/quote/latest/quote/macro.quote_spanned.html) macro from the
 /// `quote` crate but provides only just enough functionality needed by the current `macros` crate.
 macro_rules! quote_spanned {
-    ($span:expr => $($tt:tt)*) => {
-    #[allow(clippy::vec_init_then_push)]
-    {
-        let mut tokens = ::std::vec::Vec::new();
-        let span = $span;
-        quote_spanned!(@proc tokens span $($tt)*);
+    ($span:expr => $($tt:tt)*) => {{
+        let mut tokens;
+        #[allow(clippy::vec_init_then_push)]
+        {
+            tokens = ::std::vec::Vec::new();
+            let span = $span;
+            quote_spanned!(@proc tokens span $($tt)*);
+        }
         ::proc_macro::TokenStream::from_iter(tokens)
     }};
     (@proc $v:ident $span:ident) => {};

base-commit: ea76e08f4d901a450619831a255e9e0a4c0ed162
--
2.40.0